We explore the role of resource interactions in explaining firm performance in the context of acquisitions. Although we confirm that acquisitions do not lead to higher performance on average, we do find that complementary resource profiles in target and acquiring firms are associated with abnormal returns. Specifically, we find that acquiring firm marketing resources and target firm technology resources positively reinforce (complement) each other; meanwhile, acquiring and target firm technology resources negatively reinforce (substitute) one another. Implications for management theory and practice are identified.